--- title: Tasmota Flashing Day | daily.dev description: A hands-on walkthrough of flashing Tasmota firmware onto three Sonoff device models: the S31 smart plug with power monitoring, the S26 smart plug, and the... canonical: https://daily.dev/posts/tasmota-flashing-day-mgagzpqeo twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Tasmota Flashing Day | daily.dev og:description: A hands-on walkthrough of flashing Tasmota firmware onto three Sonoff device models: the S31 smart plug with power monitoring, the S26 smart plug, and the... og:url: https://daily.dev/posts/tasmota-flashing-day-mgagzpqeo og:image: https://api.daily.dev/og/posts/mGAgZpqeo.png og:image:alt: Tasmota Flashing Day og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Tasmota Flashing Day **[apalrd's adventures](https://daily.dev/sources/apalrd)** · 5 min read · 0 upvotes · 0 comments ## Summary A hands-on walkthrough of flashing Tasmota firmware onto three Sonoff device models: the S31 smart plug with power monitoring, the S26 smart plug, and the 4CHPRO R3 four-channel relay. Covers the required hardware (USB-to-serial adapter, jumper wires), the Tasmotizer flashing tool, and device-specific tips — including how to enter bootloader mode on each device, pad locations for serial connections, and which Tasmota module type to select for each. The S26 is flagged as the trickiest due to non-standard pad spacing and proximity to the power PCB, while the 4CHPRO R3 requires grounding GPIO 0 via a resistor rather than a button. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do I enter bootloader mode on a Sonoff 4CHPRO R3 to flash Tasmota? On the Sonoff 4CHPRO R3, none of the buttons map to GPIO 0 because an additional microcontroller handles IO expansion. GPIO 0 is tied to 3V3 through resistor R21. To enter bootloader mode, ground GPIO 0 by touching resistor R21 with a test lead while powering on the board. Once in bootloader mode, Tasmotizer can flash Tasmota without issues; set the module type to 'Sonoff 4CH'. _Makers flashing Sonoff devices track device-specific quirks like this on daily.dev._ ### What module type should I select in Tasmota for the Sonoff S26? Set the Sonoff S26 to the 'Sonoff S2x' module type in Tasmota. The entire S20 family shares the same firmware, with variants only for different country plug formats, so the S2x module covers the S26 and works out of the box. _Those building Tasmota-based home automation setups find device configuration tips like this on daily.dev._ ### What tool can I use to flash Tasmota firmware without manually connecting to the temporary WiFi network? Tasmotizer is a dedicated flashing tool that downloads the Tasmota image, flashes it over serial, and lets you pre-configure WiFi credentials, MQTT broker, and module type via the serial console — eliminating the need to connect to Tasmota's temporary WiFi AP for first-time setup. _Developers automating IoT device provisioning discover tools like Tasmotizer on daily.dev._ ## Similar posts on daily.dev - [The most important piece of my smart home puzzle is on sale right now; don't miss this deal](https://daily.dev/posts/the-most-important-piece-of-my-smart-home-puzzle-is-on-sale-right-now-don-t-miss-this-deal-pitimv2s6) · XDA Developers · 0 upvotes · 0 comments - [SONOFF BASIC-1GSP Matter over WiFi smart switch supports DIN rail mounting, real-time energy monitoring](https://daily.dev/posts/sonoff-basic-1gsp-matter-over-wifi-smart-switch-supports-din-rail-mounting-real-time-energy-monitor-wdwzijxsu) · CNX Software · 0 upvotes · 0 comments - [Bridging Older Tasmota Hardware Into Apple Home](https://daily.dev/posts/bridging-older-tasmota-hardware-into-apple-home-x6ecljkpe) · Hackaday · 0 upvotes · 0 comments - [Matter over Thread across VLANs](https://daily.dev/posts/matter-over-thread-across-vlans-ss2pelcrk) · /dev/io · 0 upvotes · 0 comments - [These Home Assistant Prime Day deals transformed my smart home, but one was the game-changer](https://daily.dev/posts/these-home-assistant-prime-day-deals-transformed-my-smart-home-but-one-was-the-game-changer-wovzlrgtg) · XDA Developers · 0 upvotes · 0 comments --- [View this post on daily.dev](https://daily.dev/posts/tasmota-flashing-day-mgagzpqeo) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Tasmota Flashing Day","url":"https://daily.dev/posts/tasmota-flashing-day-mgagzpqeo","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/tasmota-flashing-day-mgagzpqeo"},"datePublished":"2026-08-11T08:54:03.957Z","dateModified":"2026-08-11T09:19:28.716Z","description":"A hands-on walkthrough of flashing Tasmota firmware onto three Sonoff device models: the S31 smart plug with power monitoring, the S26 smart plug, and the...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/beb3e77edc67fd2eff6f3543116b1434?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/beb3e77edc67fd2eff6f3543116b1434?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"apalrd's adventures","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"apalrd's adventures","logo":"https://media.daily.dev/image/upload/s--4zkx8dRj--/f_auto,q_auto/v1786438309/logos/apalrd?_a=BAMAMicg0","url":"https://daily.dev/sources/apalrd"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/tasmota-flashing-day-mgagzpqeo","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"","timeRequired":"PT5M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"apalrd's adventures","item":"https://daily.dev/sources/apalrd"},{"@type":"ListItem","position":3,"name":"Tasmota Flashing Day"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/tasmota-flashing-day-mgagzpqeo#faq","mainEntity":[{"@type":"Question","name":"How do I enter bootloader mode on a Sonoff 4CHPRO R3 to flash Tasmota?","acceptedAnswer":{"@type":"Answer","text":"On the Sonoff 4CHPRO R3, none of the buttons map to GPIO 0 because an additional microcontroller handles IO expansion. 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